A lighting unit has an electronic ballast powering one or more fluorescent lamps. An electronic ballast cheaply and efficiently powers fluorescent lamps. In some types of lighting units, the fluorescent lamps are removable.
When a lamp fails, the lamp must be replaced. Usually, the power to the ballast is not turned off prior to replacement of the lamp. This causes several problems. First, present designs allow the ballast to consume large mounts of energy even if there is no lamp. Second, the voltage across the output terminals of the lamp presents a safety hazard to a person replacing the lamp.
A ballast that has reduced energy consumption when no lamp load is present, as well as reducing the shock risk to a person replacing the lamp, is thus highly desirable.